Field of the Invention
Embodiments of the invention generally relate to a medical implant and a method of operating the medical implant.
Description of the Related Art
Generally, medical endoprostheses or implants for a wide range of applications have been typically used in a large variety. Generally, implants are divided into passive and active implants. Passive implants typically tend to perform mechanical tasks in the body into which they are inserted. Passive implants are typically, for example, a stent, a replacement heart valve, a breast implant, prosthetic body limbs, or optical lenses. By contrast, generally, active implants contain an electronics unit and are able to detect specific body states or perform a treatment. Examples of active implants generally include cardiac pacemakers, neurostimulators, drug delivery pumps, or defibrillators. Typically, further applications of active implants also include sensors for body functions, for example pressure sensors as described in United States Patent Application 20020045921, to Wolinskey et al., entitled “Implantable Pressure Sensors and Methods for Making and Using Them”. Embodiments of the present invention generally relate to active implants in accordance with the above distinction, as will be further discussed below.
Generally, when using active implants, it may be necessary to exchange data relating to the control of the implant or generated by the implant, for example measurement data of a sensor integrated into the implant, with a unit that is external in relation to the implant. Typically, such a unit that is external in relation to the implant can be, for example, a unit outside the body, such as a programming apparatus or a further implant. In order to simplify the presentation, generally, a unit of the type above that is outside the body, or a further implant, will be referred to hereinafter as a further apparatus. Typically, it is desirable that a data exchange with the further apparatus is performed wirelessly. In addition, generally, the implants should be as small as possible so as to load the body to a minimal extent on account of their spatial requirement.
Typically, primarily galvanic communication/impedance modulation-based communication, inductive near-field telemetry systems or radio systems are used for data transfer between the implant and an apparatus that is outside the body for data capture and/or data processing. Typical systems, however, have a series of disadvantages. In the case of galvanic communication/impedance modulation-based communication, generally, housing feedthroughs or electrodes are necessary on the outside of the housing. In addition, typically, electrodes have to be affixed to the body surface on the side of the apparatus outside the body, which is practical only to a limited extent with frequent use of the interface. Generally, inductive near-field telemetry has a heavily limited transfer radius, in particular in the case of miniaturisation of implants and the associated use of small coils. With regard to radio data transfer, typically, there is the known disadvantage that the antenna must be of a certain size, which prevents further miniaturisation. In addition, generally, it is not possible to place the antenna in a housing made of conductive material, such as titanium, and therefore the integration of an antenna into an implant is associated with greater outlay. Typically, a further known disadvantage in the case of radio data transfer lies in the fact that the energy requirement for the data transfer rises depending on the depth of implantation of the implant in the body. Generally, this inevitably leads to the use of larger energy sources, which is also contrary to further miniaturisation.
Typically, ultrasound has also been used for the exchange of data with an implant. Generally, the systems proposed previously, however, are technically complex and take up a large amount of space. For example, the use of ultrasound for data transfer are described in the publication entitled “Deeply implanted medical device based on a novel ultrasonic telemetry technology”, thesis no. 5730 (2013) at the École Polytechnique Fédérale de Lausanne (Swiss Federal Institute of Technology in Lausanne) by M. Peisino, in U.S. Pat. No. 5,861,018, to Feierbach, entitled “Ultrasound Transdermal Communication System and Method”, in United States Patent Application Publication 20100249882, to Houben, entitled “Acoustic Telemetry System for Communication with an Implantable Medical Device”, and in United States Patent Application Publication 20020045921, to Wolinsky et al., entitled “Implantable Pressure Sensors and Methods for Making and Using Them”. The implants according to the prior art patents and publications generally have a piezoelement, with which ultrasound signals sent by an external transmission unit can be received and converted into electrical signals.
For example, U.S. Pat. No. 6,140,740, to Porat et al., entitled “Piezoelectric Transducer” generally describes a passive method for ultrasound communication in which a sound wave originating from an external transmitter is modulated in the reflection. According to Porat et al., the patient apparatus necessary for the method, and the production of the sound converter, however, are very complex.
In view of the above, there is a need of an implant having the possibility for wireless data transfer, which is of a simple structure and allows for a further miniaturisation.